Low, degraded or contaminated transmission fluid causing clutch slip; Worn or slipping clutch pack or band applied in fifth gear; Faulty input or output speed sensor, or damaged sensor wiring or connector; Shift solenoid or valve body fault, or low hydraulic pressure for the fifth gear clutch; Torque converter slip or lock-up clutch fault (automatic gearboxes); Outdated transmission control unit software where a manufacturer update is known to address the fault; Internal mechanical damage such as worn gears or selector components.

P0735

Gear 5 Incorrect Ratio.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
35: FaultThe specific fault in that area

What it means

P0735 means the transmission control unit has detected that the actual ratio between engine speed and output speed in fifth gear does not match the expected ratio. This usually points to slip or a speed sensing fault in an automatic, automated manual or dual-clutch gearbox. The code is set when the calculated ratio stays outside the allowed tolerance while fifth gear is commanded.

Symptoms

Engine revs flare or rise without matching acceleration in fifth gear
Gearbox slipping or hesitating when changing into or holding fifth
Transmission warning light or malfunction message on the dashboard
Gearbox dropping into limp mode or locking into a fixed gear
Poor fuel economy or noticeable loss of power at cruising speed
Harsh or delayed shifts between fourth, fifth and sixth

Possible causes

Low, degraded or contaminated transmission fluid causing clutch sliplikely
Worn or slipping clutch pack or band applied in fifth gearlikely
Faulty input or output speed sensor, or damaged sensor wiring or connectorpossible
Shift solenoid or valve body fault, or low hydraulic pressure for the fifth gear clutchpossible
Torque converter slip or lock-up clutch fault (automatic gearboxes)possible
Outdated transmission control unit software where a manufacturer update is known to address the faultrare
Internal mechanical damage such as worn gears or selector componentsrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting road speed, gear, fluid temperature and engine load when the fault set
Check the transmission fluid level, condition and smell, following the procedure for that model, as some gearboxes are sealed and need a specific temperature check
Inspect the speed sensor wiring, connectors and mounting for damage, corrosion, leaks or metal debris
Compare live data for input speed, output speed and engine speed, and check the calculated gear ratio in each gear
Check for other codes such as solenoid, pressure or other gear ratio faults that help narrow the cause
Test the speed sensors and solenoid circuits for resistance and signal, using the manufacturer's specifications
Carry out a road test and watch for slip under load in fifth, comparing it with the other gears
Check for any applicable software updates or technical bulletins for that model and gearbox

How to fix

Correct the fluid level or replace degraded fluid and filter using the specified type and procedure
Repair or replace damaged speed sensor wiring, connectors or faulty speed sensors
Replace faulty shift solenoids or repair the valve body as required
Overhaul or replace the gearbox or worn clutch components if internal slip is confirmed
Repair or replace the torque converter if it is found to be slipping
Update the transmission control unit software only if an official update addresses this fault

Can I keep driving?

High severity

Limit driving and avoid it where possible, as continued slip can quickly cause expensive internal damage to the gearbox. If the car must be moved, drive gently at low load and have it inspected promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.